<!-- eslint-disable vue/no-use-v-if-with-v-for -->
<template>
    <div class="pagination">
        <button :disabled="pageNo === 1" @click="$emit('getPageNo', pageNo - 1)">上一页</button>
        <button v-if="StartNumAndEndNum.start > 1" @click="$emit('getPageNo', 1)" :class="{ active: pageNo === 1 }">1</button>
        <button v-if="StartNumAndEndNum.start > 2">···</button>
        <!-- 中间部分：遍历数字 -->
        <button v-for="(page, index) in StartNumAndEndNum.end" :key="index" v-if="page >= StartNumAndEndNum.start" @click="$emit('getPageNo', page)" :class="{ active: pageNo === page }">{{ page }}</button>

        <button v-if="StartNumAndEndNum.end < totalPage-1">···</button>
        <button v-if="StartNumAndEndNum.end < totalPage" @click="$emit('getPageNo', totalPage)" :class="{ active: pageNo === totalPage }">{{ totalPage }}</button>
        <button :disabled="pageNo === totalPage" @click="$emit('getPageNo', pageNo + 1)">下一页</button>

        <button style="margin-left: 30px">共 {{ total }} 条</button>
    </div>
</template>

<script>
export default {
    name: "PageSection",
    props: ['pageNo', 'pageSize', 'total', 'continue'],
    computed: {
        totalPage() {
            // Math.ceil 向上取整
            return Math.ceil(this.total / this.pageSize)
        },
        StartNumAndEndNum() {
            let start = 0, end = 0
            // 判断总页码数有没有连续页码数大
            if(this.continue > this.totalPage) {
                start = 1,
                end = this.totalPage
            }else {
                start = this.pageNo - parseInt(this.continue / 2),
                end = this.pageNo + parseInt(this.continue / 2)
                // 判断当前页位置
                // 当前页数值不足以展示连续页
                if(start < 1){
                    start = 1,
                    end = this.continue
                }
                if(end > this.totalPage) {
                    start = this.totalPage - this.continue + 1
                    end = this.totalPage
                }
            }
            return {start, end}
        }
    }
}
</script>

<style lang="less" scoped>
.pagination {
    text-align: center;

    button {
        margin: 0 5px;
        background-color: #f4f4f5;
        color: #606266;
        outline: none;
        border-radius: 2px;
        padding: 0 4px;
        vertical-align: top;
        display: inline-block;
        font-size: 13px;
        min-width: 35.5px;
        height: 28px;
        line-height: 28px;
        cursor: pointer;
        box-sizing: border-box;
        text-align: center;
        border: 0;

        &[disabled] {
            color: #c0c4cc;
            cursor: not-allowed;
        }

        &.active {
            cursor: not-allowed;
            background-color: #409eff;
            color: #fff;
        }
    }
}
</style>